The present invention relates to the removal of moisture from the atmosphere of a transport or storage hopper for powdered or granular bulk materials. More specifically, the present invention relates to improving the flowability of powdered or granular bulk materials by using desiccant to remove an appropriate amount of moisture from the atmosphere of a transport or storage hopper.
Powdered and granular bulk materials are often shipped or stored in hoppers. Often, these materials are hygroscopic in that under certain conditions they will exchange moisture with the surrounding atmosphere. Significant changes in ambient temperature and humidity levels will trigger hygroscopic activity in the bulk material, making the bulk material difficult to discharge and unload from the hopper.
The problem is especially common in the interstate shipping industries like railroads and trucking where the bulk material contained in a hopper car or trailer is subjected to significant climatic changes as the material is transported across the country. For example, a bulk material like granular sugar, powdered flour, or cement is loaded into a covered hopper rail car in a warm humid southern state. The loaded car is then shipped to a colder northern climate. As the car moves further north, the interior surfaces of the hopper, i.e., its sidewalls, endwalls, and ceiling, become colder. The moisture in the atmosphere of the hopper condenses out of the atmosphere onto the sidewalls, endwalls, and ceiling. The moisture falls from the ceiling or runs down the walls to saturate the bulk material in various locations. The saturated bulk material may remain wet or it may dry into hardened chunks. In either case, the flowability of the bulk material is decreased, the result being that the load will not easily flow from the hopper when unloaded, especially the parts of the load that were saturated. Likewise, as the car moves it is subjected to various humidity levels, which can cause the bulk material to absorb or give-up additional moisture, again resulting in hardening or clumping of the bulk material.
Consequently, there is a need in the art for a technique for improving the flowability of hygroscopic materials from a hopper by capturing available moisture from the atmosphere within the hopper.
The present invention, in one embodiment, is a railcar for improving the flowability of sugar from a hopper. The rail car includes at least one hopper, a hatch located in an upper wall of the rail car, the hatch allowing access to the at least one hopper, and a desiccant containment device adapted to hold a desiccant, the desiccant containment device located within the hopper above a fill level and secured to the rail car within the hatch.
Another embodiment of the present invention is a method for improving the flowability of hygroscopic materials from a hopper. The method includes opening a hatch into the hopper, locating one or more desiccant containment devices within the hopper, placing a desiccant within the desiccant containment devices, and closing the hatch.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description. As will be apparent, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.